Make sure to first have SuperBLT, and BeardLib installed. Click the links in the dependency list.

Optional video tutorial for installing SuperBLT, BeardLib, and mod_overrides mods: https://youtu.be/rin_sjSJIkg

1. After downloading the mod, use a program such as 7zip or WinRAR to extract the main folder of the mod.
2. Navigate to assets/mod_overrides. The assets folder is supposed to be in your game's installation folder (don't know where that is? click here). Create the folder if necessary
3. Move the main folder of the mod from step 1 to the folder you navigated to in step 2.

The optional mods are not required, but were made with the weapon in mind.

Extract CaFCW into mod_overrides.

Extract ACH (the base mod) into the mods folder.
Color Picker is a utility associated with ACH, so throwing this in here too in the event.
To install Color Picker, extract the zip into the mods folder.

To install the Halo Crosshair pack, extract the crosshair pack into the following directory:
mods/saves/ACH Addons/Crosshairs/